It is often necessary to filter juices and other liquids during processing. For example, in the wine industry, to produce a high quality and visually appealing wine, it is necessary to filter the juices after they are extracted from the fruit.
After crushing the grapes the juice is generally allowed to settle for a period of days or weeks to allow the solids to settle out. And to avoid spoiling the juice it is necessary to chill it during this time while the settling occurs.
There are costs associated with storing the large quantities of juice and with chilling the juice. Also, the juice can degrade to some extent while it is held for an extended period waiting for the settling to occur, for example the juices can begin to oxidise and become spoiled. And in addition, the waiting period slows down the wine making process.
While fine mesh or screen filters are suitable for separating small solid particles from fluids, they generally require frequent cleaning if the fluids contains a high percentage of solids. Extracting solids from fruit juices is a classic example of this situation.
Similarly, the dewatering of effluent, for example effluent on a dairy farm, is a challenging task. The large volumes involved, and the fineness of the solids, requires dewatering apparatus with fine filtration abilities and yet the ability to perform efficiently while processing the large volumes of effluent.
To deal with these problems a range of filtering options have been used in the past. The most commonly used filtering methods tend to require the use of flocculants and/or expensive non-reusable filtration mediums. The flocculants can degrade the final product to some extent, and the used flocculants produce an additional waste disposal problem.
What is needed is an efficient filtration apparatus, which is capable of adequately filtering large quantities of juices, and which minimises or eliminates the need to use flocculants, and which minimises or eliminates the need to use throw-away filtering media.
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